U.S. Pat. No. 4,470,429 to Johnson describes an exemplary multi-port valve for use in the care and treatment of swimming pools. The two- and three-way valves of the Johnson patent include a unitary housing and a lever arm splined onto the stub of a shaft. Rotating the lever arm causes a "valve closure sealing surface" of a "closure plug" to move within the structure between various of the hubs or ports. According to the Johnson patent, the sealing surface carries both a "seal member" and an "arcuate retainer plate," the latter of which is attached to the closure plug using screws. Because the housing is unitary and the fluid passageways extend radially from it, the closure plug need never be lifted from any seated position.
U.S. Pat. No. 3,640,310 to Erlich, incorporated herein in its entirety by this reference, discloses another multi-port valve in which one or more inlet ports direct pressurized fluid through an "open central portion" to other inlet and outlet ports. Included in the valve is a rotor, which in operation interconnects various of the inlets and outlets. Attached to the rotor via a post is an elongated aluminum handle, whose manual movement is designed to change the position of the rotor. As described at column 9, lines 60-62 of the Erlich patent:
A fulcrum point is provided for the handle, so that when the handle is depressed, the post will axially lift the rotor from its seated position.
(Numerals deleted.) The valve of the Erlich patent additionally incorporates both a Teflon bearing and a metallic bearing plate, which purportedly facilitate rotation of the handle while preventing wear of the bearing. In actual use, however, consumers frequently fail to depress the handle before attempting to rotate it, often breaking (or at least prematurely wearing) the handle or the pin by which it is attached to the post.
Yet another multi-port valve marketed by Praher under the name "Eco-Valve" includes a plastic handle connected to a rotor. Rotating the handle causes a pair of rollers to travel along a plate, the upper surface of which includes four recesses of semi-circular cross-section for receiving the rollers at various intervals. Additionally incorporated into the upper surface are two opposed indentations in which the rollers may rest. Receiving the rollers in the recesses or indentations apparently helps position the rotor correctly relative to the ports of the valve. As with the device of the Erlich patent, some possibility of breaking the plastic handle exists should the force exerted by the user not translate to the rollers in a manner sufficient to permit them to be unseated from their respective recesses.